Traditional circuit switched telecommunications networks—both wired and wireless—typically base billing on connection time, such as call duration. Network elements, typically switching centers, generate records that contain user specific information about provided services for billing purposes. In the context of the circuit switched telecommunications networks these records are often called “call detail records”.
With the advent of mobile packet data telecommunications networks various packet switched services have been introduced to consumers. In such second generation (2G) mobile telecommunications networks as Global System for Mobile Communications (GSM) and Code Division Multiple Access (CDMA) networks, packet data services are typically provided with General Packet Radio Service (GPRS) technology. Third Generation Partnership Project (3GPP) mobile telecommunications networks, often based on Wideband Code Division Multiple Access (W-CDMA), also have their associated packet data services which typically are further developments of the General Packet Radio Service technology.
Packet switched data allows providing a significantly increased amount of various data services. Packet switched data also allows more billing grounds. For example, charging may be based on volumes of data transferred rather than connection time.
The increased amount of data services and their associated billing options has led to a situation in which more and more network elements process records containing user specific information about provided packet data services for billing purposes, which records are often called “charging data records (CDR)” in the context of the packet switched telecommunications networks.
There are more network elements generating the records compared to traditional circuit switched telecommunications networks. For example, Serving General Packet Radio Service Support Nodes (SGSN) and Gateway General Packet Radio Service Support Nodes (GGSN) may generate charging data records. The generated charging data records are typically collected by a charging gateway which consolidates the records and transfers them to a billing system.
Now, G-CDR, which is the charging data record generated by GGSN, is much more wildly used by the operator for the charging purpose than S-CDR, which is the charging data record generated by SGSN. In especial, with the introduction of 3G direct tunnel where the payload is transported between GGSN and RNC (Radio Network Controller) directly and SGSN is no longer able to count data volumes associated with the PDP (Packet Data Protocol) context for which the direct tunnel is established, there is no payload can be recorded in S-CDR and only G-CDR can be used for charging of 3G direct tunnel.
In brief, a PDP context activation procedure may be initiated by a MS (Mobile Station). The MS send an “Activate PDP Context Request” message, which carries information such as APN, QoS (Quality of Service Profile) requested and so on, to the SGSN. The SGSN then requests for the corresponding GGSN address according to the APN from the DNS (Domain Name System), and further sends a request for creating PDP context to GGSN after obtaining the GGSN address from the DNS. Responding to said request, the GGSN returns a “Create PDP Context Response” message to the SGSN, which carries an assigned end user address like IPv6 address, and other information such as QoS attributes, etc. After then, the SGSN sends the information derived from the GGSN to the MS via an “activate PDP Context Accept” message. Thus, the PDP activation is done.
Further, before the SGSN sends the “activate PDP Context Accept” message, the SGSN and RNC exchange information for setting up a RAB for payload traffic between the MS and the SGSN. Usually, the volume of unsuccessfully transmitted downlink data is sent to the SGSN within a “RAB assignment Response” message by RNC.
However, as for any telecommunication system using the GGSN to generate the charging data records, such as 3GPP and so forth, still creates the charging data records without including the unsuccessfully transmitted downlink data volume since the GGSN is not informed. This may result in that users are overcharged, as may give rise to a negative attitude towards a telecommunication operator and/or the services provided.
Hence, it would be desirable to make the GGSN know how much downlink data unsent by RNC if there is downlink data not transferred by RNC.